A locking device is designed in such a manner that a locking plate connected with a cylinder device is rotatably opened and closed after a key is inserted into the cylinder device to rotate the cylinder device.
A locking plate of a general locking device is mechanically connected with a cylinder device.
However, such a structure that the locking plate is mechanically connected with the cylinder device has limitation in ensuring safety essential to the locking device. Most of the locking devices are designed in such a manner that a key having no approval cannot be inserted into a cylinder device or the cylinder device cannot be rotated even if such a key is inserted into the cylinder device. However, if the cylinder device is once rotated, the locking plate is driven to open the locking device. Therefore, people who illegally try to open the locking device are likely to insert the key or another similar tool into the cylinder device to rotate the cylinder device. And, if the cylinder device is once rotated, the locking device is opened. In another case, people may drive the locking plate by destroying the cylinder device.